# Copyright (c) 2012-2014 Red Hat, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import ctypes
import os
import stat
import errno
from glusterfs import api


class File(object):

    def __init__(self, fd, path=None):
        self.fd = fd
        self.originalpath = path

    def __enter__(self):
        if self.fd is None:
            # __enter__ should only be called within the context
            # of a 'with' statement when opening a file through
            # Volume.open()
            raise ValueError("I/O operation on closed file")
        return self

    def __exit__(self, type, value, tb):
        self.close()

    def close(self):
        ret = api.glfs_close(self.fd)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def discard(self, offset, len):
        ret = api.client.glfs_discard(self.fd, offset, len)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def dup(self):
        dupfd = api.glfs_dup(self.fd)
        if not dupfd:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return File(dupfd, self.originalpath)

    def fallocate(self, mode, offset, len):
        ret = api.client.glfs_fallocate(self.fd, mode, offset, len)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def fchown(self, uid, gid):
        """
        Change this file's owner and group id

        :param uid: new user id for file
        :param gid: new group id for file
        :returns: 0 if success, raises OSError if it fails
        """
        ret = api.glfs_fchown(self.fd, uid, gid)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def fdatasync(self):
        """
        Force write of file

        :returns: 0 if success, raises OSError if it fails
        """
        ret = api.glfs_fdatasync(self.fd)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def fstat(self):
        """
        Returns Stat object for this file.
        """
        s = api.Stat()
        rc = api.glfs_fstat(self.fd, ctypes.byref(s))
        if rc < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return s

    def fsync(self):
        ret = api.glfs_fsync(self.fd)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def lseek(self, pos, how):
        """
        Set the read/write offset position of this file.
        The new position is defined by 'pos' relative to 'how'

        :param pos: sets new offset position according to 'how'
        :param how: SEEK_SET, sets offset position 'pos' bytes relative to
                    beginning of file, SEEK_CUR, the position is set relative
                    to the current position and SEEK_END sets the position
                    relative to the end of the file.
        :returns: the new offset position

        """
        return api.glfs_lseek(self.fd, pos, how)

    def read(self, buflen, flags=0):
        rbuf = ctypes.create_string_buffer(buflen)
        ret = api.glfs_read(self.fd, rbuf, buflen, flags)
        if ret > 0:
            return rbuf
        elif ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        else:
            return ret

    def write(self, data, flags=0):
        # creating a ctypes.c_ubyte buffer to handle converting bytearray
        # to the required C data type

        if type(data) is bytearray:
            buf = (ctypes.c_ubyte * len(data)).from_buffer(data)
        else:
            buf = data
        ret = api.glfs_write(self.fd, buf, len(buf), flags)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret


class Dir(object):

    def __init__(self, fd):
        # Add a reference so the module-level variable "api" doesn't
        # get yanked out from under us (see comment above File def'n).
        self._api = api
        self.fd = fd
        self.cursor = ctypes.POINTER(api.Dirent)()

    def __del__(self):
        self._api.glfs_closedir(self.fd)
        self._api = None

    def next(self):
        entry = api.Dirent()
        entry.d_reclen = 256
        rc = api.glfs_readdir_r(self.fd, ctypes.byref(entry),
                                ctypes.byref(self.cursor))

        if (rc < 0) or (not self.cursor) or (not self.cursor.contents):
            return rc

        return entry


class Volume(object):

    # Housekeeping functions.

    def __init__(self, host, volid, proto="tcp", port=24007):
        # Add a reference so the module-level variable "api" doesn't
        # get yanked out from under us (see comment above File def'n).
        self._api = api
        self.fs = api.glfs_new(volid)
        api.glfs_set_volfile_server(self.fs, proto, host, port)

    def __del__(self):
        self._api.glfs_fini(self.fs)
        self._api = None

    def set_logging(self, path, level):
        api.glfs_set_logging(self.fs, path, level)

    def mount(self):
        return api.glfs_init(self.fs)

    def chown(self, path, uid, gid):
        """
        Change owner and group id of path

        :param path: the item to be modified
        :param uid: new user id for item
        :param gid: new group id for item
        :returns: 0 if success, raises OSError if it fails
        """
        ret = api.glfs_chown(self.fs, path, uid, gid)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def exists(self, path):
        """
        Test whether a path exists.
        Returns False for broken symbolic links.
        """
        try:
            self.stat(path)
        except OSError:
            return False
        return True

    def getatime(self, path):
        """
        Returns the last access time as reported by stat
        """
        return self.stat(path).st_atime

    def getctime(self, path):
        """
        Returns the time when changes were made to the path as reported by stat
        This time is updated when changes are made to the file or dir's inode
        or the contents of the file
        """
        return self.stat(path).st_ctime

    def getmtime(self, path):
        """
        Returns the time when changes were made to the content of the path
        as reported by stat
        """
        return self.stat(path).st_mtime

    def getsize(self, filename):
        """
        Return the size of a file, reported by stat()
        """
        return self.stat(filename).st_size

    def getxattr(self, path, key, maxlen):
        buf = ctypes.create_string_buffer(maxlen)
        rc = api.glfs_getxattr(self.fs, path, key, buf, maxlen)
        if rc < 0:
            err = ctypes.get_errno()
            raise IOError(err, os.strerror(err))
        return buf.value[:rc]

    def isdir(self, path):
        """
        Test whether a path is an existing directory
        """
        try:
            s = self.stat(path)
        except OSError:
            return False
        return stat.S_ISDIR(s.st_mode)

    def isfile(self, path):
        """
        Test whether a path is a regular file
        """
        try:
            s = self.stat(path)
        except OSError:
            return False
        return stat.S_ISREG(s.st_mode)

    def islink(self, path):
        """
        Test whether a path is a symbolic link
        """
        try:
            s = self.lstat(path)
        except OSError:
            return False
        return stat.S_ISLNK(s.st_mode)

    def listdir(self, path):
        """
        Return list of entries in a given directory 'path'.
        "." and ".." are not included, and the list is not sorted.
        """
        d = self.opendir(path)
        dir_list = []
        while True:
            ent = d.next()
            if not isinstance(ent, api.Dirent):
                break
            name = ent.d_name[:ent.d_reclen]
            if not name in [".", ".."]:
                dir_list.append(name)
        return dir_list

    def listxattr(self, path):
        buf = ctypes.create_string_buffer(512)
        rc = api.glfs_listxattr(self.fs, path, buf, 512)
        if rc < 0:
            err = ctypes.get_errno()
            raise IOError(err, os.strerror(err))
        xattrs = []
        # Parsing character by character is ugly, but it seems like the
        # easiest way to deal with the "strings separated by NUL in one
        # buffer" format.
        i = 0
        while i < rc:
            new_xa = buf.raw[i]
            i += 1
            while i < rc:
                next_char = buf.raw[i]
                i += 1
                if next_char == '\0':
                    xattrs.append(new_xa)
                    break
                new_xa += next_char
        xattrs.sort()
        return xattrs

    def lstat(self, path):
        s = api.Stat()
        rc = api.glfs_lstat(self.fs, path, ctypes.byref(s))
        if rc < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return s

    def makedirs(self, name, mode=0777):
        """
        Create directories defined in 'name' recursively.
        """
        head, tail = os.path.split(name)
        if not tail:
            head, tail = os.path.split(head)
        if head and tail and not self.exists(head):
            try:
                self.makedirs(head, mode)
            except OSError as err:
                if err.errno != errno.EEXIST:
                    raise
            if tail == os.curdir:
                return
        self.mkdir(name, mode)

    def mkdir(self, path, mode=0777):
        ret = api.glfs_mkdir(self.fs, path, mode)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def open(self, path, flags, mode=0777):
        if (os.O_CREAT & flags) == os.O_CREAT:
            #Without direct call to _api the functest fails on creat and open.

            fd = api.client.glfs_creat(self.fs, path, flags, mode)
        else:
            fd = api.client.glfs_open(self.fs, path, flags)
        if not fd:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))

        return File(fd, path)

    def opendir(self, path):
        fd = api.glfs_opendir(self.fs, path)
        if not fd:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return Dir(fd)

    def removexattr(self, path, key):
        ret = api.glfs_removexattr(self.fs, path, key)
        if ret < 0:
            err = ctypes.get_errno()
            raise IOError(err, os.strerror(err))
        return ret

    def rename(self, opath, npath):
        ret = api.glfs_rename(self.fs, opath, npath)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def rmdir(self, path):
        ret = api.glfs_rmdir(self.fs, path)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def rmtree(self, path, ignore_errors=False, onerror=None):
        """
        Delete a whole directory tree structure. Raises OSError
        if path is a symbolic link.

        :param path: Directory tree to remove
        :param ignore_errors: If True, errors are ignored
        :param onerror: If set, it is called to handle the error with arguments
                        (func, path, exc) where func is the function that
                        raised the error, path is the argument that caused it
                        to fail; and exc is the exception that was raised.
                        If ignore_errors is False and onerror is None, an
                        exception is raised
        """
        if ignore_errors:
            def onerror(*args):
                pass
        elif onerror is None:
            def onerror(*args):
                raise
        if self.islink(path):
            raise OSError("Cannot call rmtree on a symbolic link")
        names = []
        try:
            names = self.listdir(path)
        except OSError as e:
            onerror(self.listdir, path, e)
        for name in names:
            fullname = os.path.join(path, name)
            if self.isdir(fullname):
                self.rmtree(fullname, ignore_errors, onerror)
            else:
                try:
                    self.unlink(fullname)
                except OSError as e:
                    onerror(self.unlink, fullname, e)
        try:
            self.rmdir(path)
        except OSError as e:
            onerror(self.rmdir, path, e)

    def setxattr(self, path, key, value, vlen):
        ret = api.glfs_setxattr(self.fs, path, key, value, vlen, 0)
        if ret < 0:
            err = ctypes.get_errno()
            raise IOError(err, os.strerror(err))
        return ret

    def stat(self, path):
        s = api.Stat()
        rc = api.glfs_stat(self.fs, path, ctypes.byref(s))
        if rc < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return s

    def statvfs(self, path):
        """
        To get status information about the file system that contains the file
        named by the path argument.
        """
        s = api.Statvfs()
        rc = api.glfs_statvfs(self.fs, path, ctypes.byref(s))
        if rc < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return s

    def symlink(self, source, link_name):
        """
        Create a symbolic link 'link_name' which points to 'source'
        """
        ret = api.glfs_symlink(self.fs, source, link_name)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def unlink(self, path):
        """
        Delete the file 'path'

        :param path: file to be deleted
        :returns: 0 if success, raises OSError if it fails
        """
        ret = api.glfs_unlink(self.fs, path)
        if ret < 0:
            err = ctypes.get_errno()
            raise OSError(err, os.strerror(err))
        return ret

    def walk(self, top, topdown=True, onerror=None, followlinks=False):
        """
        Directory tree generator. Yields a 3-tuple dirpath, dirnames, filenames

        dirpath is the path to the directory, dirnames is a list of the names
        of the subdirectories in dirpath. filenames is a list of the names of
        the non-directiry files in dirpath
        """
        try:
            names = self.listdir(top)
        except OSError as err:
            if onerror is not None:
                onerror(err)
            return

        dirs, nondirs = [], []
        for name in names:
            if self.isdir(os.path.join(top, name)):
                dirs.append(name)
            else:
                nondirs.append(name)

        if topdown:
            yield top, dirs, nondirs
        for name in dirs:
            new_path = os.path.join(top, name)
            if followlinks or not self.islink(new_path):
                for x in self.walk(new_path, topdown, onerror, followlinks):
                    yield x
        if not topdown:
            yield top, dirs, nondirs